Gearlike tools are known for precision machining of gears and have hard-material grains embedded in a binding agent or have a toothed metallic base member with tooth flanks which have hard-material grains embedded in a binding agent. The hard-material grains can, for example, be grains of cubic boronnitride (CBN). These known tools are exposed to a certain amount of wear during use and must be dressed from time to time in order to again obtain their original profile. The dressing tools which are used for this dressing include, as a rule, a toothed metallic base member with a coating of diamond grains which are embedded in a binding agent. The dressing tools often have dimensions substantially identical to those of the gears which are machined by the precision machining tools which are to be dressed, because with this a retooling of the machine for the dressing operation is not needed; the dressing tools are fed to the machine in place of the gears and are removed after the dressing.
Particularly in the case of tooth systems with a small modulus, producing an even coating with the diamond grains at times creates considerable difficulties, since a galvanic or other treatment in the relatively narrow gaps between teeth often yields unsatisfactory results. The cause for this is to be seen in the closely side-by-side tooth flanks on each side of each tooth gap, through which the diamond grains are deflected during the coating operation.
Due to this, a basic purpose of the invention is to provide a gearlike dressing tool of the above-mentioned type, in which the described difficulties during coating do not occur.
In addition to the attainment of this purpose, a further purpose, insofar as it is possible at the same time, is to make possible the solution to yet another problem which occurs in such dressing tools, namely, to reduce the enormous amount of time required for grinding the tooth flanks of the dressing tool. In the interest of the work result during precision machining, the precision machining tool must be true to form within small tolerances. This, however, can be achieved only with a very exact dressing tool. The dressing tools which are coated with the diamond grains must therefore be ground with a diamond grinding disk. The material thereby removed from the dressing tool per unit time is naturally very small.